1. Field of the Invention
The present invention relates to a dynamic amount sensor for detecting a dynamic amount of an angular velocity, an acceleration or the like applied to a body, and particularly relates to a dynamic amount sensor of an electrostatic capacitance detecting type for detecting an applied dynamic amount or quantity based on a change in an electrostatic capacitance.
2. Description of the Related Art
A dynamic amount sensor of an acceleration sensor or an angular velocity sensor is used in a wide field of a hand blurring correcting apparatus of a video camera, an air bag apparatus for vehicle mount use, an attitude control apparatus of a robot and the like.
In the dynamic amount sensors, there is a sensor of an electrostatic capacitance detecting type for detecting a displacement of a mass by a change in an electrostatic capacitance between a movable electrode provided at a mass (mass body) constituting a movable member and a fixed electrode provided to face the movable electrode in an opposed manner and detecting a dynamic amount based on the displacement of the mass.
There is used a C/V (electrostatic capacitance/voltage) connecting apparatus for converting an electrostatic capacitance into a voltage in correspondence therewith for detecting a change in the electrostatic capacitance between a movable electrode and a fixed electrode in a dynamic amount sensor of an electrostatic capacitance detecting type.
A patent reference described below proposes a technology in which in a dynamic amount sensor of an electrostatic capacitance detecting type using a C/V converting apparatus (converting circuit), a dynamic amount operated in a plurality of axial directions is detected by a single sensor.
Patent Reference 1: JP-A-2004-279261
Patent Reference 1 proposes an acceleration sensor of a two-axis detection type including a sensor element portion in which a capacitance is changed in accordance with an acceleration in x-axis direction and a sensor element portion in which a capacitance is changed in accordance with an acceleration in y-axis direction.
In details, there is constructed a constitution in which the accelerations are outputted based on changes in electrostatic capacitances between movable electrodes and fixed electrodes exclusive for respective detecting axes in the sensor element portions provided in correspondence with the respective detecting axes.
Patent Reference 1 proposes a technology in which an x-axis signal processing circuit and a y-axis signal processing Circuit are operated by switching sampling timings thereof in order to restrain crosstalk (interference with cross axis).
The acceleration sensor described in Patent Reference 1 is constituted to alternately detect the acceleration in x-axis direction and the acceleration in y-axis direction while switching the sampling timings.
Therefore, for example, during a time period of detecting the acceleration in the sensor element portion in x-axis direction on one side, the sensor element portion in y-axis direction on other side is brought into an unfunctioned state (rest state).
Therefore, according to the acceleration sensor described in Patent Reference 1, the sensor element portions provided at inside of the sensor, that is, the fixed electrodes for detection are not effectively utilized.